Method of manufacturing dynamo-brushes, &amp;c.



UNITED STATES PATENT OFFICE.

Gnome EGLY, vor BERLIN,

GERMANY, ASSIGNOR TO GEBR'U'DER SIEMENS & 00., QF CHARLOTTENBURG, GERMANY.

METHOD OF MANUFACTURING DYNAMO-BRUSHES, &c.

942,379, Ho Drawing.

To all whom it mag concern:

-Be itknown that I, Gnonc EGLY, a subject of German Emperor, residing at Frankfurter Allee. 154/155, Berlin, Germany, have invented certain new and useful Methods of Manufacturing Dynamo-Brushes, Sliding Contacts, and Similar Electrically-Conducting Bodies, &c., of which the following is a specification.

The present invention relates to a method of manufacturing dynamobrushes, sliding contacts and similar electrically conducting bodies which are subjected tofriction, and

has for its object to render the resulting products more suitable for the purposes to which they are applied.

In accordance with the present invention silicon is added to thecarbon' in the manuwhich are exposed to friction; The silicon is finely ground or powdered and is very I intimately mixed with the carbon, and the taine A0 mixture thus obtained then undergoes the processes of molding and heating in the usual manner. Carbons which are obtained in this manner which contain a percentage of silicon are very hard and are excellent means for olishing a commutator.

In accor ance with the present invention it is preferable to heat the molded mixture of carbon and silicon in a, nitrogenous atmosphere, or in pure nitrogen, order to convert the silicon into a compound of silicon and nitrogen or intoa compound of nitrogen, silicon and carbon. In this manner a very uniform binding of the entire mass and great homogeneity of the,body is ob- The kind of compound which is formed Specification of Letters Patent. Application filed January 25, 1907. Serial No. 354,128. (Specimena) by nitrogen combining with silicon may be very-different; when a sufficient quantity of siliconis employed and when the mixture is sufliciently heated, apparently the chemical compound C Si 'N is formed.

The quantity of silicon which is'to be mixed with the carbon depends entirely on the properties which the finished brush or sliding contact is to have. Generally speaking it may be said that with an increasing percentage of silicon the hardness of the finished body increases, whereas the conduc tivity' decreases. For most purposes additions of from 25%' of silicon prove quite sufficient in order to obtain a brush or slid ing contact of excellent conductivity and simultaneously of great hardness and one which is capable of polishing very well.

What I claim as my invention and desire to secure by Letters Patent is t 1. A method of manufacturing dynamo brushes and other sliding contacts, consisting in mixing powdered silicon intimately with powdered carbon, in molding'the mixture thus obtained and in heating said mixture in a nitrogenous atmosphere.

2. A method of manufacturing dynamo brushes and other sliding contacts, consisting in mixing triturated silicon intimately with powdered carbon in molding the mixture thus'obtained and inheating said mixture in nitrogen.

In testimony whereof I have signed my name to this specification in the presence of the two subscribing witnesses.

WoLoE AR HAUPT, HENRY HASPER.

Patented Dec. 7, 1909. i 

